Barry Irby
Mark touched on a number of important things.

As a Home Inspector I have seen an evolution in generators. It used to be that we saw small to medium sized portable units in peoples garages and sheds and when the power failed, the owner would drag them out and set them up. This required keeping fuel (gasoline) on hand and then running out for more.

A truly terrifying aspect of this setup was how they got connected to the house. Some used cords that plugged into the dryer plug. Some people had cords hanging out of the bottom of the panel. Some people wired slightly more permanent plugs. The message here is, DON'T use any of these. Be sure to get a proper transfer switch. This will either manually or automatically separate your house service from the power company and connect it to the generator. This is very important. Without the transfer switch if you get mixed up you could start the generator first sending power backwards down the power lines and injure the very people trying to repair the system.

So, Mark is right. Be sure you have a proper fuel supply, It may be nearly impossible to even gt to a service station and even if you can they may not have power to pump the gas or may not have gasoline to pump.

Get a quality unit.

Consider the size. Do you need to run the whole house, or can you separate it into perhaps a smaller zone and run a limited number of things. Be careful what you choose to run and not run. I recently saw a house with two panels, one for the generator and one that would not be used during a power failure. The problem was they were going to run the well so they could have water and flush the toilets, but had not realized there was a pump in the septic system. Not going to flush much without that pump.